The British Labour Party will table a Parliamentary no-confidence motion in the Conservative government in a bid to force a general election.
The vote could be held as soon as Wednesday, but its timing amid the most hotly-contested Tory leadership race in living memory could render it no more than a political stunt.
Official opposition leader Sir Keir Starmer's party threatened the move late last week after Prime Minister Boris Johnson announced he was stepping down as party leader but staying on at 10 Downing Street until his successor for both jobs was elected in September.
If a majority of MPs vote in favour of the no-confidence motion, it could force a snap general election — although potentially the Queen could ask another Conservative to form a new government without going to the polls.
James Murray, Labour's shadow financial secretary to the treasury told Sky News that Labour felt "forced" to call the vote after the Conservative 1922 Committee did not force Johnson out of office — a move beyond its power — and that the vote was the "the last opportunity" to remove Johnson before Parliament rises for the summer break next week.
"A lot of them resigned en masse recently. All of them have voted against Boris Johnson," Murray said. "I think the whole country realises that he just has no integrity and honesty."
But with the government still holding a real-terms majority of 73 MPs, it would take a major rebellion to win the vote.
Two major imperatives are at work against that outcome. Any Conservative voting against the government would likely lose the party whip, which would disqualify them from standing, nominating or voting in the leadership contest in which they hope to see their preferred candidate elected.
Labour also holds a polling lead of more than ten percentage points since Johnson's resignation, enough to lose scores of Tories their seats in a snap election.
By contrast, an orderly leadership transition would give the new PM until January 2025 to regain faith in the party before they would have to go to the polls.